Abstract: In this book and in its companion volumes, Warrant: The Current Debate and Warranted Christian Belief, I examine the nature of epistemic warrant, that quantity enough of which distinguishes knowledge from mere true belief. In Warrant: The Current Debate, the first volume in this series, I considered some of the main contemporary views of warrant. In this book, the second in the series, I present my own account of warrant, arguing that the best way to construe warrant is in terms of proper function. In my view, a belief has warrant for a person if it is produced by her cognitive faculties functioning properly in a congenial epistemic environment according to a design plan successfully aimed at the production of true or verisimilitudinous belief. In the first two chapters of this volume, I fill out, develop, qualify, and defend this view, exploring along the way some of the convoluted contours of the notion of proper function. In the next seven chapters, I consider how the proposed account works in the main areas of our cognitive design plan: memory, introspection, knowledge of other minds, testimony, perception, a priori belief, induction, and probability. Then, in Ch. 10, I consider broader, structural questions of coherentism and foundationalism. My account of warrant meets the conditions for being a naturalistic account; but in Chs. 11 and 12, I claim that naturalism in epistemology flourishes best in the context of supernaturalism in metaphysics. For, as I argue in Ch. 11, there appears to be no successful naturalistic account of the notion of proper function. In Ch. 12, I argue, further, that metaphysical naturalism when combined with contemporary evolutionary accounts of the origin and provenance of human life is an irrational stance; it provides for itself an ultimately undefeated defeater.

Keywords: a priori, coherentism, epistemology, foundationalism, induction, memory, naturalism, probability, proper function, testimony, warrant